U.S. patent number 5,850,560 [Application Number 08/700,109] was granted by the patent office on 1998-12-15 for audio control circuit for a computer system system having an energy-saving feature.
This patent grant is currently assigned to Chuntex Electronic Co., Ltd.. Invention is credited to Chang-lung Kang.
United States Patent |
5,850,560 |
Kang |
December 15, 1998 |
Audio control circuit for a computer system system having an
energy-saving feature
Abstract
To allow sounds to be output by the audio amplifier of a
multi-media computer system during periods of CPU inactivity and
display screen blanking, a switch is added to the control circuit
of the audio amplifier which overrides the energy-saving shut-down
program which would normally be activated to cut-off power to both
the monitor display screen and the audio amplifier. The switch is
in the form of a transistor whose control electrode is connected to
both the power supply and to the CPU, such that the transistor can
be turned on either by a signal from the main power circuit or by a
keyboard activated signal from the CPU's microprocessor, the
collector of the transistor being connected to the audio input
terminal of the audio amplifier.
Inventors: |
Kang; Chang-lung (Taipei,
TW) |
Assignee: |
Chuntex Electronic Co., Ltd.
(Taipei Hsien, TW)
|
Family
ID: |
21625783 |
Appl.
No.: |
08/700,109 |
Filed: |
August 20, 1996 |
Foreign Application Priority Data
|
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|
|
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Apr 18, 1996 [TW] |
|
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85205600 |
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Current U.S.
Class: |
713/324 |
Current CPC
Class: |
G06F
1/32 (20130101) |
Current International
Class: |
G06F
1/32 (20060101); G06F 001/32 () |
Field of
Search: |
;395/750.03,750.05,750.06 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Auve; Glenn A.
Attorney, Agent or Firm: Bacon & Thomas, PLLC
Claims
I claim:
1. An audio control circuit for a computer system having a CPU
including a microprocessor, a monitor, and an audio amplifier, and
means for switching to an energy-saving state by shutting down the
monitor when the CPU is inactive for a predetermined period of
time,
wherein said computer system further includes means for maintaining
a supply of power to said audio amplifier when said computer system
is in said energy-saving state,
wherein said means for maintaining a supply of power to said audio
amplifier is a switch circuit controlled by an audio signal output
terminal of the microprocessor and connected between a power
circuit an audio input of the audio amplifier, and
wherein said switch circuit comprises:
a transistor having a control electrode connected to the audio
signal output terminal of the microprocessor such that when the
control electrode of the transistor is in a first state, an input
terminal of the audio amplifier is cut-off, and when the control
electrode of the microprocessor is in a second state, the input
terminal of the microprocessor is allowed to receive audio signals,
and
means connected between the control electrode of the transistor and
a power circuit for switching the monitor to an energy-saving state
by switching said transistor from said second state to said first
state, wherein said output terminal of the microprocessor is
arranged to override the energy-saving means and switch said
transistor from the first state to the second state in response to
activation of a switch controlling said output terminal.
2. A circuit as claimed in claim 1, further comprising a diode
connected between the audio output of the microprocessor and said
control electrode of the transistor, the cathode of said diode
being on the side of the diode connected to the microprocessor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an audio control circuit for a computer
system of the type having an audio amplifier, and in particular to
a circuit which can control the audio output of the computer system
so that sound can be listened to through the audio amplifier even
when the computer system is in an energy-saving state and the video
display of the monitor is cut-off.
2. Discussion of Related Art
Computers play an increasingly significant role in everyday life,
at home and particularly at work. Computers are of course
convenient because of their capability of processing large amounts
of data using relatively complex operations in a very short time.
It is of course conventional to display information and results of
an operation performed by the computer as an image on a video
monitor.
Recently, however, the role of computers in everyday life has
expanded to include recording and playback of sounds as well as
images, greatly expanding potential uses for the computer,
including replacement of stand-alone audio components. A computer
normally requires a central processing unit (CPU), a peripheral
storage device such as a disk drive, and a monitor for displaying
information, but for so-called "multi-media" systems, which include
both image and sound reproduction capabilities, an audio amplifier
is also required.
Because of their mass storage capabilities, compact disc read only
memories (CD-ROMS) are generally associated with such systems,
although the term "multi-media" is intended to be inclusive of all
computer systems with both image and sound capabilities. When a
CD-ROM drive in used with the computer system's audio amplifier,
music can be transferred directly from the CD-ROM player in the
manner of a stand-alone CD player, by-passing the central
processing unit.
To save power, an energy-saving device is often included which
causes the CPU to issue an instruction to switch the monitor and
other non-essential systems into an energy-saving state so as to
avoid wasting energy when the system is inactive. While this is a
highly desirable feature, it causes a problem when sounds are being
played back through the audio amplifier in a way that allows the
CPU to remain inactive for extended periods of time, such as when
music CDs are being played back via the computer system's CD-ROM
player. The problem is that because the energy-saving state is
usually initiated based on a lack of CPU activity, shut-down will
occur in this situation even though sound is being reproduced
through the audio amplifier, thereby interfering with the user's
enjoyment of the music.
While one could deactivate the energy saving function, it would be
more desirable to maintain the energy saving function as it applies
to the screen, and to instead include an arrangement for
maintaining the audio output even when the energy-saving function
is in effect and the power supply to the monitor screen has been
cut-off.
SUMMARY OF THE INVENTION
It is accordingly an objective of the invention to provide an audio
control circuit for a multi-media computer system which prevents
the audio amplifier from being turned off when the computer is in
an energy-saving state, without affecting application of the
energy-saving feature to the visual display of the monitor, thereby
permitting energy savings to be obtained without interfering with
audio reproduction.
This objective is accomplished by adding to the conventional audio
amplifier control circuit a direct input from the microprocessor,
including a switch connected to the audio amplifier in such a
manner that the state of the switch determines whether the
amplifier is on or off, and in such a manner that the switch in
normally controlled to turn the amplifier off during the
energy-saving state. By adding to the on/off switch of the audio
amplifier a direct input from the microprocessor, the switch can be
made to permit operation of the amplifier even when the switch
would ordinarily cause the amplifier to turn off.
In an especially preferred embodiment of the invention, the switch
is a transistor whose control electrode is connected to both the
power supply and to the microprocessor, such that the transistor
can be turned on either by a signal from the main power circuit or
by the direct signal from the microprocessor, the collector of the
transistor being connected to an on/off input of the audio
amplifier.
More particularly, in the illustrated embodiment, the base of the
transistor is connected via a diode to the audio "mute" terminal of
the microprocessor, which is normally set at a low voltage to
permit operation of the audio amplifier but which switches to a
high voltage to shut down the audio amplifier. A button or other
input device controls the audio signal output terminal of the
microprocessor so that when the CPU switches the monitor to the
energy saving state and attempts to switch the transistor to a high
state, the normal function of the audio amplifier can be maintained
depending on the state of the button by overriding the
energy-saving circuit to keep the transistor in a low state,
thereby allowing the audio amplifier to be independently supplied
with power from the monitor power circuit and sound to be heard
even when the visual display is not being used and the CPU is
inactive for a long period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a functional block diagram of the present invention.
FIG. 2 is a schematic circuit diagram showing details of a
preferred embodiment of the invention generally illustrated in FIG.
1.
FIG. 3 is a schematic circuit diagram showing an application of the
preferred embodiment to a particular monitor circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, the present invention includes a
microprocessor 10, a switching circuit 20, an audio amplifier 30, a
keyboard 40, and power circuit 50. The audio amplifier 30, which
may be built-in to or integral with the monitor, normally operates
to output audio signals retrieved from an audio source such as a
CD-ROM player to a speaker (not shown) when the CPU is in a normal
working state, and is normally shut down when the CPU switches to
an energy saving state because the CPU has been inactive for a
predetermined period of time.
As illustrated in FIG. 2, the audio amplifier IC301, which is a
commercially available integrated circuit, includes a terminal 7
connected to a volume control made up of resistors VR301 and R304
which controls the voltage input from the power circuit 50 via
transistor Q303. A transistor Q302 activated by a control signal
supplied by the power circuit serves to shut-off power input to
terminal 7 of the audio amplifier when the power circuit is
deactivated to save energy upon receiving an "inactive" signal from
the microprocessor 10.
In order to prevent shut down of the audio amplifier when
transistor Q302 is switched, an output terminal of the
microprocessor which is activated by a switch SW1 on keyboard 40 is
connected through a switch to the audio amplifier in such a manner
that when the CPU switches the monitor to the energy saving state,
the normal function of the audio amplifier is maintained, allowing
the audio amplifier can be independently used and sound can be
heard, for example from a CD-ROM player, even when the CPU is not
being used. This is accomplished, as described in more detail
below, by connecting an output terminal of the microprocessor
directly to a switch Q301 in the form of a transistor having a
control electrode connected to both transistor Q302 and the output
terminal of the microprocessor, and a collector electrode (or
emitter electrode depending on the transistor configuration)
connected to the audio amplifier input terminal 7 such that when
switch 0302 is turned on, the audio amplifier is cut off and when
switch Q302 is turned off, the audio amplifier is permitted to
operate normally.
It will of course be appreciated by those skilled in the art that
the terms "high" and "low" as used herein are relative terms, and
that the exact voltages and circuit elements will depend on the
nature of the microprocessor, audio amplifier, and transistor
switches, and further that in some systems the output in question
might need to be set at a high rather than low voltage in order to
maintain operation of the audio amplifier, with the details of the
circuit to be described below varying accordingly.
In operation, the switch Q301 shown in FIG. 2 (and also in FIG. 3)
maintains the audio amplifier in an operating state based on the
state of audio terminal 23 of microprocessor IC501, terminal 23
being connected, through a series-connected diode D302 having a
cathode on the microprocessor side of the diode, to the base or
control electrode of transistor Q301. The base of transistor Q301
is also connected to power circuit 50, which is conventional in
nature and which includes the energy-saving feature whereby the
power supply is essentially shut-down upon receiving a signal from
the microprocessor and whereby during shut down, a signal supplied
from the power circuit to the control electrode of transistor Q301
switches from low to high, turning on transistor Q301 and
effectively shorting out the terminal 7 of the audio amplifier
IC301, which controls its output state. Because of the connection
between the control electrode of transistor Q301 and the
microprocessor, however, if the output terminal of the
microprocessor is in a low state, the control electrode of the
transistor Q301 will be held in a low state, preventing the
amplifier from being turned off.
Those skilled in the art will appreciate that the preferred
embodiment makes use of the microprocessor's "audio mute" terminal,
which is normally activated to silence the audio amplifier during
normal operation. The difference with the conventional circuit is
that, in the preferred embodiment, when the mute button SW1 on
keyboard 40 is pushed, the corresponding output of the
microprocessor is connected to maintain power to the audio
amplifier rather than shut-off the amplifier.
Referring to FIG. 3, which shows the same circuits as in FIG. 2,
but with the addition of video processing circuitry for use in a
monitor, it can be seen that when the present invention is used in
a monitor, the switching circuit cooperates with both the
conventional image and audio reproduction circuits shown therein so
that when the monitor is being used normally, IC 301 can maintain
its function as an audio amplifier. In an energy saving state, when
switch SW1 is activated by a user of the system, IC501 takes over
control of the audio amplifier IC301 and maintains its function so
that music or other sounds can continue to be output by the audio
amplifier. If switch SW1 is not activated, the audio amplifier is
shut down with the video display screen.
In summary, the present invention maintains the function of an
audio amplifier, by controlling a transistor connected to an audio
output terminal of a microprocessor when the monitor is in an
energy-saving state and the monitor display is turned off.
Having thus described various preferred embodiments of the
invention, those skilled in the art will appreciate that variations
and modifications of the preferred embodiment may be made without
departing from the scope of the invention. It is accordingly
intended that the invention not be limited by the above description
or accompanying drawings, but that it be defined solely in
accordance with the appended claims.
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